Scenario:

You have a metadata column you want to update, but how to do this?

Objective:

You want to update the status field, with a new status from that term set.

Steps

Identify the List and Item

Like always, I’ll use varsitename in the URL, and in the URI Varlistname and VaritemID.

Execute the HTTP Request

With this request, I’m updating the name_status field. I will have to have queried the term store before, to get the filter array for the status field I want to have it updated to.

I unfortunately cannot simply say status:newstatus.

Method: POST
Uri: _api/web/lists/getbytitle('@{variables('VarListname')}')/items(@{variables('VarItemID')})/validateUpdateListItem

Body: 
{
 "formValues": [
  {
      "FieldName": "Name_Status",
      "FieldValue": "itemlabel|@{body('Filter_array')[0]?['id']}"
  }
 ]
}